Indium source reagent compositions, and use thereof for deposition of indium-containing films on substrates and ion implantation of indium-doped shallow junction microelectronics structures

ABSTRACT

An indium precursor composition having utility for incorporation of indium in a microelectronic device structure, e.g., as an indium-containing film on a device substrate by bubbler or liquid delivery MOCVD techniques, or as a dopant species incorporated in a device substrate by ion implantation techniques. The precursor composition includes a precursor of the formula R 1 R 2 InL wherein: R 1  and R 2  may be same or different and are independently selected from C 6 -C 10  aryl, C 6 -C 10  fluoroaryl, C 6 -C 10  perfluoroaryl, C 1 -C 6  alkyl, C 1 -C 6  fluoroalkyl, or C 1 -C 6  perfluoroalkyl; and L is β-diketonato or carboxylate. Indium-containing metal films may be formed on a substrate, such as indium-copper metallization, and shallow junction indium ion-implanted structures may be formed in integrated circuitry, using the precursors of the invention.

GOVERNMENT RIGHTS IN INVENTION

The invention hereof was made with Government funding assistance underContract No. DMI-9660730 awarded by the National Science Foundation. TheGovernment has certain rights in the invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an indium source reagent composition havingutility for incorporation of indium in a microelectronic devicestructure, e.g., as an indium-containing film on a device substrate bybubbler or liquid delivery MOCVD techniques, or as a dopant speciesincorporated in a device substrate by ion implantation techniques. Theinvention also relates to such semiconductor fabrication techniques forusing the indium source reagent of the invention, as well as tomicroelectronic device structures incorporating indium by use of suchsource reagent and techniques.

2. Description of the Related Art

In the field of semiconductor manufacturing, indium is a material ofconsiderable current and future technological importance.

With the emergence and proliferation of copper as a preferred materialin metallization for formation of conductor transmission lines ofintegrated circuitry devices, copper-indium (Cu/In) alloys are of greatinterest for improving the long-term performance, electro-migrationresistance and reliability of copper-based interconnects.Indium-containing III-V semiconductor materials also will play anincreasingly important role in the development of electronic andoptoelectronic devices.

The most commonly used In precursors for the deposition of In-basedmaterials are trialkylindium, such as trimethylindium andtriethylindium. For the chemical vapor deposition (CVD) of Cu/In alloys,such conventional In precursors are not compatible with currently usedCu precursors, when multiple source precursors (for In and Cu) areintroduced. In addition, the conventional In precursors are extremelysensitive to air, oxygen and moisture, leading to vigorous exothermicreactions, fire and explosions when exposed to such ambient atmosphericconstituents.

Indium also is of great current interest in the microelectronics fieldas a potential dopant species for the formation of doped shallowjunctions in integrated circuitry devices, since shallow devicejunctions enable high performance devices to be fabricated at lowerswitching voltages than are required for junctions of greater depth.Further, in relation to other dopant species that may be employed forforming doped junction structures by conventional ion implantationtechniques, indium has the significant advantage that its size and massallow lower implant energies to be used, provided that useful beamcurrents of In ions can be obtained.

The beam current is a critical aspect of the ion implantation operationas practiced in conventional ion implanter systems, and is stronglyprecursor material-dependent in character. Specifically, thevaporization and delivery of the precursor for ionization and ion beamtransport of the implant species typically requires a material ofsuitable volatility and transport characteristics, but volatile liquidsand solids when used as precursors also create a potential risk ofintroduction of reactive species that are susceptible to side-reactionsand also create the potential for contamination of the substrate anddisruption of the desired device characteristics.

Given these circumstances, there is a compelling need in the art for newIn precursors suitable for deposition of In-based materials or ionimplantation of In in semiconductor device structures.

SUMMARY OF THE INVENTION

This invention relates in one aspect to an indium source reagentcomposition useful for incorporating indium in a microelectronic devicestructure, e.g., as an indium-containing film on a device substrate bybubbler or liquid delivery MOCVD techniques, or as a dopant speciesincorporated in a device substrate by ion implantation techniques.

The invention also relates to such semiconductor fabrication techniquesfor using the indium source reagent of the invention, as well as tomicroelectronic device structures incorporating indium by use of suchsource reagent and techniques.

In one aspect, the invention relates to an indium precursor compositionof the formula:

R₁R₂InL

wherein:

R₁ and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, orC₁-C₆ fluoroalkyl C₁-C₆ perfluoroalkyl; and

L is β-diketonato or carboxylate.

Another aspect of the invention relates to an indium precursorcomposition of the formula:

wherein:

R′ and R″ may be the same or different and are independently selectedfrom H, C₆-C₁₀ aryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl, and C₁-C₆ perfluoroalkyl; and

R₁ and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl, or C₁-C₆ perfluoroalkyl.

Still another aspect of the invention relates to a method of making adialkyl(β-diketonate)indium(III) compound, by the reaction:

InR₃+H(β-diketonate)→(β-diketonate)InR₂+RH

or

InR₂X+M(β-diketonate)→(β-diketonate)InR₂+MX or

InR₃+H(carboxylate)→(carboxylate)lnR₂+RH or

InR₂X+M(carboxylate)→(carboxylate)InR₂+MX

wherein:

each R may be same or different and is independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl and; M is selected from Li, Na, or Kand; X is selected from F, Cl, Br or I.

In a further aspect, the invention relates to a liquid deliverymetal-organic chemical vapor deposition process for forming aIn-containing film on a substrate, comprising:

providing a liquid precursor composition including an indium precursorof the formula:

R₁R₂InL

wherein:

R₁ and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl; and

L is β-diketonato or carboxylate;

flash vaporizing the precursor to form a precursor vapor;

transporting the precursor vapor to a chemical vapor deposition reactorcontaining a substrate element; contacting the precursor vapor with thesubstrate element in the chemical vapor deposition reactor underchemical vapor deposition conditions, to form an In-containing film onthe substrate element.

A further aspect of the invention relates to a method of ionimplantation of In+ions in a substrate, comprising ionizing an indiumprecursor composition to produce an ionization product includingIn+ions, separating In+ions from the ionization product, and directingthe separated In+ions under ion implantation conditions into thesubstrate, wherein the indium precursor composition comprises an indiumprecursor of the formula:

R₁R₂InL

wherein:

R₁ and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl; and

L is β-diketonato or carboxylate.

Still another aspect of the invention relates to a microelectronicdevice structure comprising a shallow junction region containing In+ionsderived from ionization of an indium precursor composition comprising anindium precursor of the formula:

R₁R₂InL

wherein:

R₁ and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl; and

L is β-diketonato or carboxylate.

The invention further relates to a microelectronic device structureincluding conductor transmission lines comprising an indium-coppercomposition formed by chemical vapor deposition of indium and copperfrom precursor material therefor, wherein said precursor materialcomprises an indium precursor of the formula:

R₁R₂InL

wherein:

R₁ and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl; and

L is β-diketonato or carboxylate.

Other aspects, features and embodiments of the invention will be morefully apparent from the ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an STA plot for (hfac)In(CH₃)₂.

FIG. 2 is an Ortep diagram of the molecular structure of (hfac)In(CH₃)₂.

FIG. 3 is an Energy Dispersive Spectroscopy (EDS) spectrum of Cu(In)alloy deposited from (hfac)In(III)(CH₃)₂.

DETAILED DESCRIPTION OF THE INVENTION, AND PREFERRED EMBODIMENTS THEREOF

The present invention is based on the discovery that when one or more ofthe alkyl groups of a trialkylindium compound is replaced by aβ-diketonate or carboxylate, its reactivity decreases significantly,while the volatility of the resulting compound is substantiallyincreased, to a level that has been found to be consistent with utilityof the compound for chemical vapor deposition and ion implantation.Further, such substituted organoindium compounds have been found to beunexpectedly stable in exposure to air, oxygen and moisture.

The disclosures of the following United States patents and patentapplications are hereby incorporated herein by reference in theirentirety:

U.S. patent application Ser. No. 08/835,768 filed Apr. 8, 1997 in thenames of Thomas H. Baum, et al.;

U.S. patent application Ser. No. 08/484,654 filed Jun. 7, 1995 in thenames of Robin A. Gardiner et al.;

U.S. patent application Ser. No. 08/414,504 filed Mar. 31, 1995 in thenames of Robin A. Gardiner et al.;

U.S. application Ser. No. 08/280,143 filed Jul. 25, 1994, in the namesof Peter S. Kirlin, et al.;

U.S. patent application Ser. No. 07/927,134, filed Aug. 7, 1992 in thesame names;

U.S. patent application Ser. No. 07/807,807, filed Dec. 13, 1991 in thenames of Peter S. Kirlin, et al., now issued as U.S. Pat. No. 5,204,314;

U.S. application Ser. No. 08/181,800 filed Jan. 15, 1994 in the names ofPeter S. Kirlin, et al., and issued as U.S. Pat. No. 5,453,494;

U.S. application Ser. No. 07/918,141 filed Jul. 22, 1992 in the names ofPeter S. Kirlin, et al., and issued Jan. 18, 1994 as U.S. Pat. No.5,280,012;

U.S. application Ser. No. 07/615,303 filed Nov. 19, 1990;

U.S. application Ser. No. 07/581,631 filed Sep. 12, 1990 in the names ofPeter S. Kirlin, et al., and issued Jul. 6, 1993 as U.S. Pat. No.5,225,561; and

U.S. patent application Ser. No. 07/549,389 filed Jul. 6, 1990 in thenames of Peter S. Kirlin, et al.

The compounds of the present invention have the formula:

R₁R₂InL

wherein:

R₁ and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl; and

L is β-diketonato or carboxylate.

Preferred β-diketonate In precursors of the invention have the formula:

wherein:

R′ and R″ may be the same or different and are independently selectedfrom H, C₆-C₁₀ aryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl, and C₁-C₆ perfluoroalkyl; and

R₁ and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl.

The β-diketonate moiety of the In precursor compound of the inventionmay be any suitable β-diketonate moiety that can be coordinated to theIn metal atom and is effective to form a complex of the desiredstability, solubility and volatility characteristics. Illustrative ofβ-diketonate species that may be usefully employed in the broad practiceof the present invention are the following:

2,2,6,6-tetramethyl-3,5-heptanedionate (“thd”);

2,2,6-trimethyl-3,5-heptanedione (“Hthd”);

1,1,1,2,2,3,3,-heptafluoro-7,7-dimethyl-octane-4,6-dionate (“fod”);acetylacetonate (“acac”);

1,1,1-trifluoroacetylacetonate (“tfac”);

1,1,1,5,5,5,-hexafluoroacetylacetonate (“hfac”); and

2,2,7-trimethyl-3,5-octanedionate (“tod”).

The precursor may for example be of the formula R₁R₂In(hfac), wherein R₁and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl. Specific examples of the precursorinclude (CH₃)₂In(hfac) and (CF₃)₂In(hfac).

The precursor compounds of the invention can be synthesized by thereaction:

InR₃+H(β-diketonate)→(β-diketonate)InR₂+RH or

InR₂X+M(β-diketonate)→(β-diketonate)InR₂+MX or

InR₃+H(carboxylate)→(carboxylate)InR₂+RH or

InR₂X+M(carboxylate)→(carboxylate)InR₂+MX

wherein:

each R may be same or different and is independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl and;

M is selected from Li, Na, or K and;

X is selected from F, Cl, Br or I.

Dialkyl(β-diketonate)indium(III) compounds of the invention can besynthesized by a direct reaction of trialkylindium and β-diketone asexpressed in the equation 1:

InR₃+H(β-diketonate)→(β-diketonate)InR₂+RH   (1)

wherein:

each R may be the same or different and is alkyl.

A corresponding reaction can be carried out to form thedialkyl(carboxylate)indium (III) compounds of the invention, using acarboxylic acid as a coreactant with the trialkylindium startingmaterial, wherein the carboxylate may be formate, trifluoroacetate,pivalate and alkyl, fluoroalkyl or perfluoroalkyl carboxylate.

Dialkyl(β-diketonate)indium(III) compounds of the invention can be alsosynthesized by a salt-elimination reaction as expressed in equation 2:

InR₂X+M(β-diketonate)→(β-diketonate)InR₂+MX   (2)

wherein each R may be the same or different and is alkyl. Acorresponding reaction can be carried out to form thedialkyl(carboxylate)indium (III) compounds of the invention, using acarboxylic acid as a coreactant with the trialkylindium startingmaterial, wherein the carboxylate may be formate, trifluoroacetate,pivalate and alkyl, fluoralkyl or perfluoroalkyl carboxylate.

The (β-diketonate)InR₂ and (carboxylate)InR₂ compositions of theinvention are highly effective source reagents for use in the depositionof In-containing materials, and may readily be used in place ofconventional In precursors. The compositions and methodology of theinvention provide the following advantages:

1). the precursor compositions of the invention are: i) air and moisturestable, ii) highly volatile and thermally stable, iii) compatible withCu CVD precursors; and

2). MOCVD and ion implant processes using the precursor compositions ofthe invention provide a safer, more reliable and more effective way fordepositing In-containing materials or of implanting In in substratematerials.

The In-containing materials, which can be metallic alloy or III-Vsemiconductor materials, can be deposited by thermal decomposition of(dialkyl)In(III)(β-diketonate) precursors. For the deposition of Cu/Inalloy, the alloy films may be formed by depositing In metal onto Cufilms directly, or by depositing the two elements simultaneously fromdual bubblers.

In some cases, it may be advantageous to decompose the precursor in thepresence of a reducing co-reactant (e.g., H₂) to preferentially depositIn metal.

The alloy films may also be deposited using a single bubbler fordelivering a mixture of the In and Cu precursors.

For the deposition of III-V semiconductor materials, the precursor canbe decomposed in the presence of Group V co-reagents (e.g., AsH₃, PH₃,or SbH₃) to deposit InAs, InP or InSb, respectively.

In the broad practice of the present invention involving the use of theprecursors for deposition of In-containing films, either a bubblerdelivery system or a liquid delivery technique can be used fordeposition of the In-containing materials. In the liquid deliveryapproach, the liquid precursor can be delivered for the CVD of theIn-containing material thin films using (β-diketonate)In(Ill)(dialkyl)in a suitable solvent medium that is compatible with the In precursor,e.g., hydrocarbons (aliphatic or aromatic), organic amines, polyamines,organic ethers, organic esters, alkyl nitrites, alkanols, glymes,tetraglymes, and solvent mixtures of suitable solvent species such asfor example alkane solvent species in combination with amine orpolyamine solvent species. In the bubbler delivery approach theprecursor can be delivered for the CVD of the In-containing materialthin films using (β-diketonate)In(III)(dialkyl) neat.

Specific types of solvents may include: glyme solvents having from 1 to20 ethoxy repeating units, C₂-C₁₂ alkanols, organic ethers selected fromthe group consisting of dialkyl ethers comprising C₁-C₆ alkyl moieties,C₄-C₈ cyclic ethers, C₈-C₄₀ crown, O₁-O₂₀ ethers wherein the prefixedC_(i) range is the number i of carbon atoms in the ether compound andthe suffixed O_(i) range is the number i of oxygen atoms in the ethercompound, C₆-C₁₂ aliphatic hydrocarbons, C₆-C₁₈ aromatic hydrocarbons,and organic esters, amines and polyamines. Specific solvent speciesinclude tetrahydrofuran, alkyl acetate, tetraglyme and C₃-C₈ alkanols.

It will be recognized that the foregoing is of an illustrativecharacter, and that a wide variety of solvent media may be employed inthe broad practice of the invention.

The liquid delivery process of the invention may include the provisionof multiple precursors including the In precursor of the invention andother precursors, such as a Cu precursor for the formation ofindium-copper interconnects, an aluminum precursor for AIInN filmformation, a Ga precursor for GaInN film formation, etc. The respectiveprecursor compositions may be combined in a single multicomponentprecursor medium as a “cocktail” including all of the metal species tobe deposited to form the product multicomponent metal film, oralternatively, separate precursor compositions may be separatelyvaporized and the resulting vapor then combined in the manner more fullydescribed in co-pending U.S. patent application Ser. No. 08/758,599filed Nov. 27 1996 in the names of J. Roeder et al. for “MultipleVaporizer Reagent Supply System for Chemical Vapor Deposition UtilizingDissimilar Precursor Compositions,” the disclosure of which hereby isincorporated herein by reference in its entirety.

The invention thus contemplates the provision of single as well asmultiple vaporizer zones for generating the precursor vapor from thecorresponding precursor composition(s) including the In precursor of theinvention. The flash vaporization may be carried out in a singlevaporizer to generate the In precursor vapor, or alternatively, multiplevaporizer units may be employed, for flash vaporization of respectiveprecursor compositions including the separate In precursor compositionof the invention. Where the precursor compositions include solventmedia, different solvent media may be employed in the respective ones ofthe multiple precursor compositions.

The flash vaporizer zone may be constructed and arranged as more fullydescribed in U.S. Pat. No. 5,536,323 issued Jul. 16, 1996 in the namesof Peter S. Kirlin et al., U.S. Pat. No. 5,711,816 issued Jan. 27, 1998in the names of Peter S. Kirlin et al., and U.S. Pat. No. 5,204,314issued Apr. 20, 1993 in the names of Peter S. Kirlin et al., thedisclosures of which hereby are incorporated herein by reference intheir entireties.

A chemical vapor deposition reactor may also be provided in precursorvapor-receiving relationship to the vaporizer or the bubbler, andconstructed and arranged as more fully described in the incorporated byreference U.S. Patents described in the preceding paragraph.

The precursor vapor deriving from flash vaporization of the precursorcomposition is flowed directly or carried by a carrier gas into thechemical vapor deposition reactor. The carrier gas may be of anysuitable type that is non-deleteriously employed with the precursorvapor. Illustrative of suitable gas species which may potentially beuseful in the broad practice of the present invention are argon,nitrogen, helium, ammonia, etc. The carrier gas functions to entrain andmix with the precursor vapor to provide a precursor gas mixture which istransmitted to the chemical vapor deposition chamber.

The precursor vapor mixture may be mixed in the chemical vapordeposition reactor with an oxidizing co-reactant gas if an In-containingmetal oxide film is desired to be formed. The oxidizing co-reactant gasmay be of any suitable type providing an oxygen-containing environmentin which the In-containing metal oxide film may be formed on thesubstrate.

The substrate for such purpose may be suitably retained at a desiredtemperature, as for example in the range of from about 100° C. to about1200° C., by appropriate heating means, which may for example utilize aresistably heated susceptor structure on which the substrate is mounted,infrared heating means, inductively coupled heating arrangements, orother heat transfer or heat exchange means whereby the substrate ismaintained at the desired temperature for deposition on the substrate ofthe desired In-containing material films.

The oxidizing co-reactant gas when employed may comprise oxygen gas(O₂), ozone, singlet oxygen, N₂O, or other oxic gas, or active oxidizingspecies, e.g., from a remote plasma source. The chemical vapordeposition reactor is maintained at a suitable pressure, e.g., of fromabout 0.1 torr to about 760 torr, and the chemical vapor deposition iscarried out for sufficient time to provide growth of the In-containingmaterial films to a desired thickness, as for example a thickness in therange of from about 0.01 micron to about 200 microns. The chemical vapordeposition reactor may be equipped with a showerhead-type distributorfor influent gaseous/vapor streams, e.g., a showerhead device of thetype described in U.S. patent application Ser. No. 08/402,142 filed Mar.10, 1995 in the names of Peter C. Van Buskirk et al. for“Showerhead-Type Discharge Assembly for Delivery of Source Reagent Vaporto a Substrate, and CVD Process Utilizing Same” and U.S. patentapplication Ser. No. 08/621,088 filed Mar. 22, 1996 in the names ofPeter C. Van Buskirk et al. for “Interiorally Partitioned Vapor Injectorfor Delivery of Source Reagent Vapor Mixtures for Chemical VaporDeposition,” the disclosures of which hereby are incorporated byreference herein in their entireties.

The precursors of the invention may be used to provide In-Cuinterconnects in microelectronic device manufacture, as well as theformation of III-V semiconductor materials for electronic andoptoelectronic applications.

In ion implantation applications, the precursors of the invention may beused to generate a suitable ion beam of In+ for ion implantation ofindium ions in a microelectronic device structure. For such purpose, abubbler or liquid delivery technique may be used to achieve transport ofthe precursor to the ion implanter. Compositions of the invention forion implantation may suitably comprise perfluorinated (β-diketonate)InR₂or (acetate)InR₂ compositions which by virtue of their fluorinesubstituents act to assist the cleaning and etching of the ion sourceand implanter electro-optic components, thereby serving to removecarbonaceous deposits from such equipment.

The In precursors of the invention enable In+ doping to form shallowjunctions for the manufacture of high performance microelectronicdevices.

Examples of microelectronic device structures that are usefullyfabricated utilizing the In deposition and implantation processes and Inprecursor compositions of the invention include transistors such asmetal-oxide-semiconductor field effect transistors (MOSFETs), NMOS, PMOSand CMOS transistor devices, MESFETs, bipolar junction transistors,capacitor structures, memory cells, etc.

The indium precursor of the invention may also be utilized for formingIn-Cu metallization elements, e.g., conductor transmission lines andinterconnects, in integrated circuitry applications.

The features and advantages of the invention are more fully shown by thefollowing non-limiting examples, wherein all parts and percentages areby weight, unless otherwise expressly stated.

EXAMPLE 1

In this example, (hfac)In(CH₃)₂ was synthesized, and utilized for CVD ofIn.

1). Synthesis of (hfac)In(CH₃)₂: The general reaction was carried outunder a steady flow of nitrogen. A Schlenk flask was charged with 4.80 g(30 mmol) of trimethylindium and 20 mL diethyl ether.1,1,1,5,5,5-hexafluoroacetylacetone (6.20 g, 30 mmol) was added dropwiseto the magnetically stirred solution at about −10° C. After theaddition, the clear solution was stirred for one hour at roomtemperature. Removal of volatiles yielded 9.5 g (˜90%) whiteneedle-shaped crystals.

2). Characterization: The crystalline product was characterized bysolution NMR (¹H and ¹³C). The NMR data were consistent with themolecular formula of (hfac)In(CH₃)₂. Sublimation and STA results (seeFIG. 1) showed that (hfac)In(CH₃)₂ can be sublimated intact. STA dataalso showed that (hfac)In(CH₃)₂ has a low melting point (63° C.) andthus may be used as a liquid In source for CVD at a temperature above63° C.

To determine the degree of oligomerization of (hfac)In(CH₃)₂ in solidstate, single crystals were grown by sublimation of the compound at roomtemperature under an atmospheric pressure. Suitable crystal material wasselected and characterized by single crystal X-ray diffraction. Themolecular structure is shown in the Ortep diagram of FIG. 2.

3). Stability study: i). A small amount of crystalline (hfac)In(CH₃)₂was exposed to air in a vial for at least 2 days. No reactions wereobserved visually or by ¹H NMR. These observations revealed that(hfac)In(CH₃)₂ is stable to air and water moisture.

Stability study: ii). To study the compatibility of (hfac)In(CH₃)₂ with(hfac)Cu(I)A, wherein A=a neutral Lewis base ligand, a small amount of(hfac)In(CH₃)₂ and (hfac)Cu(I)A, where A=dimethylcyclooctadiene(“DMCOD”) or 2-methyl-1-hexen-3-yne (“MHY”), were mixed and dissolved inC₆D₆ in a NMR tube. ¹H NMR results indicated that no reaction tookplace.

For comparison, trimethylindium and (hfac)Cu(I)A were mixed together inC₆D₆; a yellow gel precipitation formed initially, then the yellowprecipitation quickly turned into black particles. Further studyrevealed the reaction led to the formation of Cu metal (black particles)and (hfac)In(CH₃)_(2.)

4). CVD study: The chemical vapor deposition of Cu(In) alloys wasstudied using (hfac)In(III)(CH₃)₂ as a precursor. Copper-indium alloyswere formed by depositing In on Cu-coated Pt/Si substrates at 300° C. ina warm-wall belljar CVD reactor without carrier gas. The reactorpressure was maintained between 0.9-2.0 Torr. Under these conditions, aCu(In) alloy film was formed. A film was analyzed by Energy DispersiveSpectroscopy (EDS) and the spectrum is shown in FIG. 3.Semi-quantitative EDS results revealed that the ratio of In: Cu : Pt ofthe film was 1:5:4.

While the invention has been illustratively described herein withreference to various embodiments and disclosed features, it will beappreciated that the invention is not thus limited, but rather extendsto and encompasses numerous variations, modifications and otherembodiments. Accordingly, the invention is intended to be broadlyconstrued and interpreted as including all such variations,modifications and other embodiments within the spirit and scope thereof,as hereinafter claimed.

What is claimed is:
 1. An indium precursor composition of the formula:R₃R₂InL wherein: R₁ and R₂ may be same or different and areindependently selected from C₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀perfluoroaryl, C₁-C₆ alkyl, C₁-C₆ fluoroalkyl, or C₁-C₆ perfluoroalkyl;and L is β-diketonato or carboxylate, with the proviso that R₁ and R₂are not simultaneously both methyl or butyl.
 2. The composition of claim1, wherein L is β-diketonato.
 3. The composition of claim 1, wherein Lis carboxylate.
 4. The composition of claim 1, wherein L is selectedfrom the group consisting of: 2,2,6,6-tetramethyl-3,5-heptanedionate;2,2,6-trimethyl-3,5-heptanedione;1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-octane-4,6-dionate;acetylacetonate; 1,1,1-trifluoroacetylacetonate;1,1,1,5,5,5-hexafluoroacetylacetonate; and2,2,7-trimethyl-3,5-octanedionate.
 5. An In precursor of the formula:

wherein: R′ and R″ may be the sane or different and are independentlyselected from H, C₆-C₁₀ aryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl, and C₁-C₆ perfluoroalkyl; and R₁ and R₂ may be same ordifferent and are independently selected from C₆-C₁₀ aryl, C₆-C₁₀fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆ fluoroalkyl, orC₁-C₆ perfluoroallyl with the proviso that R₁ and R₂ are notsimultaneously both methyl or butyl.
 6. The precursor of claim 5,wherein R′ and R″ may be the same or different and are independentlyselected from C₁-C₆ alkyl, C₁-C₆ fluoroalkyl, and C₁-C₆ perfluoroalkyl.7. The precursor of claim 5, wherein R′ and R″ may be the same ordifferent and are independently selected from C₁-C₆ alkyl.
 8. An Inprecursor of the formula:

wherein R′ and R″ may be the same or different and are independentlyselected from C₁-C₆ fluoroalkyl; and R₁ and R₂ may be same or differentand are independently selected from C₆-C₁₀ aryl, C₁-C₁₀ fluoroaryl,C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆ fluoroalkyl or C₁-C₆perfluoroalkyl.
 9. An In precursor of the formula:

wherein R′ and R″ may be the same or different and are independentlyselected from C₁-C₆ perfluoroalkyl, and R₁ and R₂ may be same ordifferent and are independently selected from C₆-C₁₀ aryl, C₆-C₁₀fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆ fluoroalkyl orC₁-C₆ perfluoroalkyl.
 10. The precursor of claim 5, wherein R₁ and R₂may be same or different and are independently selected from C₁-C₆alkyl, C₁-C₆ fluoroalkyl, and C₁-C₆ perfluoroalkyl.
 11. The precursor ofclaim 5, wherein R₁ and R₂ may be same or different and areindependently selected from C₁-C₆ alkyl.
 12. An In precursor of theformula:

wherein; R′ and R″ may be same or different and are independentlyselected from H, C₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl,C₁-C₆ alkyl, C₁-C₆ fluoroalkyl or C₁-C₆ perfluoroalkyl; and R₁ and R₂may be same or different and are independently selected from C₁-C₆fluoroalkyl.
 13. An In percusor of the formula:

wherein: R′ and R″ may be same or different and are independentlyselected from H, C₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl,C₁-C₆ alkyl, C₁-C₆ fluoroalkyl or C₁-C₆ perfluoroaLkyl; and R₁ and R₂may be same or different and are independently selected from C₁-C₆perfluoroalkyl.
 14. A composition comprising R₁R₂In(hfac), wherein: R₁and R₂ may be same or different and are independently selected fromC₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀ perfluoroaryl, C₁-C₆ alkyl, C₁-C₆fluoroalkyl or C₁-C₆ perfluoroalkyl; and hfac is1,1,1,5,5,5-hexafluoroacetylacetonate.
 15. The composition according toclaim 14, wherein R₁ and R₂ may be same or different and areindependently selected from C₁-C₆ alkyl.
 16. The composition accordingto claim 14, wherein each of R₁ and R₂ is methyl.
 17. The compositionaccording to claim 14, wherein R₁ and R₂ may be same or different andare independently selected from C₁-C₆ fluoroalkyl.
 18. The compositionaccording to claim 14, wherein R₁ and R₂ may be same or different andare independently selected from C₁-C₆ perfluoroalkyl.
 19. Thecomposition according to claim 14, wherein each of R₁ and R₂ istrifluoromethyl.
 20. The composition of claim 3, wherein the carboxylateis selected from formate, acetate, pivalate, alkyl, fluoroalkyl, orperfluoroalkyl carboxylate.
 21. The composition of claim 20, wherein thecarboxylate is acetate.
 22. An indium precursor composition of theformula: R₁R₂InL wherein: R₁ and R₂ may be same or different and areindependently selected from C₆-C₁₀ aryl, C₆-C₁₀ fluoroaryl, C₆-C₁₀perfluoroaryl, C₁-C₆ fluoroalkyl, or C₁-C₆ perfluoroalkyl; and L isβ-diketonato or carboxylate.